Of course, an application might have its own idea about what Shift- -Y means! An application's own key bindings always trump those in the Services menu. Services know when the current application has a binding that conflicts with theirs and might try to offer alternative keystrokes, changing its binding indicator in the Services menu to reflect this. If all of its bindings raise conflicts, it stops trying altogether, and can only be used through the Services menu for that particular application. Logging Out and Shutting Down When you're done using your Macintosh, there are two ways to bring your session to a close: shutting down, and logging out. Because Mac OS X is a multiple-user system and a server platform, you should choose to shut down the computer only if nobody else on your local network is using it or the services it provides. This includes both the other human users on the system, who might be logged into it remotely (see Section 7.5 in Chapter 7) or using network-shared vol- umes (see Section 13.7), as well as people or programs using any running network services (described in Chapter 7). For example, if you are using printer sharing (as described in Chapter 8) to let other computers in your home or office use the printer connected to your Macintosh, then